EVE Online theorycrafting and history

Turret Mechanics (Part 1) – Roll For Initiative(dot)

The easiest way that I’ve found to explain turret mechanics is a throwback that should make immediate sense to tabletop RPG players:

Every time you activate a turret, the Eve engine calculates a chance-to-hit percentage. You then roll a 100-sided die (D100), and use the following rules:

If you roll a 1, you get a crit (wrecking blow) — a guaranteed hit for triple damage. [1]

If you roll any other number less than or equal to your chance-to-hit, you hit.

If you roll a number greater than your chance-to-hit, you miss.

When you hit on any number other than a 1, you take your roll, add 50, and treat the sum as a percentage of your turret’s base damage. So, assuming that you’re shooting a stationary target at optimal range (100% chance to hit), each roll of the dice can produce a hit ranging from 50% of base damage (a glancing blow) to 150% of base damage (a penetrating/smashing shot).

As your chance-to-hit starts dropping, not only do you start having rolls that miss, but your highest quality shots are the first ones to get converted to misses. For example, lets say that you have a 75% chance to hit a target; that means you hit on a roll of 1-75, and miss on a roll of 75-00. That means that you will never hit for more than 125% of your base damage; you cannot get penetrating shots. As it drops off, not only do you have more chances to do no damage on a shot, but your shots that hit will be of increasingly lower quality.

This is the main way that damage drops off with range, and it’s particularly important for alpha-strike doctrines; fighting in falloff doesn’t only reduce your fleet-wide average damage per cycle due to misses, but it dramatically depresses individual volley damage as well. Likewise for shooting targets with tiny signature radii.

The other crucial part of turret mechanics is how we actually compute the chance-to-hit percentage. That’s complex enough to be its own topic, and it’ll be in the next post.

1. Wrecking shots aren’t actually a guaranteed hit — you can only get a wrecking shot if you have a non-zero chance to hit, even if it’s very small. Imagine that you’re in an artillery Tornado with Quake loaded, and an AB Taranis is orbiting you at 500m; you have a near-zero chance to hit it, due to tracking, but it’s still a tiny fraction above zero. Thus, wrecking shots are possible. Now, imagine that the same Taranis is 225km away; you have a strictly zero chance to hit with EMP, even if both you and it are completely stationary. You will never hit it, even if you roll a one.